Circuit breaker with improved tripped latch means

ABSTRACT

A circuit breaker with a trip latch mechanism characterized by relatively movable contacts and a latch member releasable to effect automatic opening of the contacts. The latch member being retained in the latched position by latch means comprising a roller, latch lever, and a linkage mechanism in which the roller is mounted on the latch lever and retaining the latch arm in the latched position, the linkage mechanism including an overcenter toggle for holding the latch lever in the latched position, and means for releasing the overcenter toggle so that the latch lever is movable to the unlatch position.

United States Patent [191 Maier et al.

CIRCUIT BREAKER WITH IMPROVED TRIPPED LATCH MEANS Inventors: Alfred E. Maier; Robert H. Hill,

both of Beaver Falls, Pa.

Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

Filed: May 30, 1974 Appl. No.: 474,855

US. Cl. 335/22; 335/ 191; 200/DIG. 42 Int. Cl. H01H 77/00 Field of Search 335/21, 22, 166, 191; 1 200/DIG. 42

References Cited UNITED STATES PATENTS 9/1961 Maier ..335/191 1/1965 Bodenschatz ..335/191 [451 Dec. 23, 1975 3,624,329 11/1971 Fischer et a1. 335/191 X Primary Examiner--G. Harris Attorney, Agent, or FirmL. P. Johns [57] ABSTRACT ,A circuit breaker with a trip latch mechanism characterized by relatively movable contacts and a latch member releasable to effect automatic opening of the contacts. The latch member being retained in the latched position by latch means comprising a roller, latch lever, and'a linkage mechanism in which the roller is mounted on the latch lever and retaining the latch arm in the latched position, the linkage mechanism including an overcenter toggle for holding the latch lever in the latched position, and means for releasing the overcenter toggle so that the latch lever is movable to the unlatch position.

9 Claims, 4 Drawing Figures US. Patent Dec. 23, 1975 Sheet 2 of 3 3,928,826

lr/ w X/f/l/ll CIRCUIT BREAKER WITH IMPROVED TRIPPED LATCH MEANS BACKGROUND OF THE INVENTION '3 over the prior art in that means are utilized to provide a force reduction through the latch structure with reduced friction as well as to provide a more compact unit.

SUMMARY OF THE INVENTION It has been found in accordance with this invention that an improved protective device may be provided for a circuit breaker which comprises relatively movable contact means and releasable means to effect opening of said contact means, the releasable means including a releasable arm movable between latched and unlatched positions, latch means latching the releasable arm and comprising a roller, a latch lever, and a linkage mechanism, the roller being mounted on the latch lever for retaining the releasable arm in the latched position, the latch lever being pivotally mounted for movement between latched and unlatched positions, the linkage mechanism comprising an overcenter toggle for holding the latch lever in the latched position, and release means operable to release the overcenter toggle so that the latch lever is movable to the unlatched position.

The advantage of the device of this invention is that it provides a latch structure with reduced friction so that there is a force reduction with a corresponding reduction in size to enable the use of standard circuit breaker framework. In addition, it enables the use of the positive-on advantage so that the manual handle of the circuit breaker remains in the on position if the contacts are welded together, and the breaker is unlatched.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view with parts broken away of a circuit breaker embodying the principlesof this invention;

FIG. 2 is an enlarged elevational view partly in section showing the trip device of FIG. 1;

FIG. 3 is a horizontal sectional view taken on the line IIIIll of FIG. 2;

FIG. 4 is an enlarged elevational view of another embodiment of the trip device shown in FIG. 1; and

FIG. 5 is a horizontal sectional view taken on the line VV of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A circuit breaker, generally indicated at 7 in FIG. 1, corresponds to that disclosed in US. Pat. No. 3,560,683 for which reason the description herein is limited to only the primary operating parts.

The circuit breaker 7 comprises an insulating housing including a molded insulating base 9 with a detachable cover 11 which housing is separated by suitable insulating barrier means into three adjacent insulating compartments for housing three full units of the multi-pole 2 circuit breaker in a manner known in the art. In each pole unit a pair of solderless terminals 15 and 17 are provided at opposite ends of the associated compartment to enable connection of the circuit breaker to an electric circuit.

In each of the three pole-unit compartments of the circuit breaker there are a pair of spaced conductors 19 and 21, a stationary contact 23 on the conductor 19, a movable contact 25 on a contact arm 27, and a flexible conductor 29 which extends between the contactarm and the conductor 21. The conductor 21 is electrically connected by associated conductors 31 and 33 to the terminal 17. A circuit passing through the circuit breaker 7 extends from the terminal 15 through the elements 19, 23, 25, 27, 29, 21, 31, 33 to the terminal 17. Although the contact arm 27 is shown in the open position, the closed position is shown in broken lines with the contacts 23, 25 in the closed circuit position.

A single operating mechanism, generally indicated at 35, for controlling all three circuit poles, is mounted in the center pole unit of the circuit breaker. The operating mechanism 35 comprises a frame 37 that comprises spaced supporting plate parts, mounted on the base 9, a pivoted forked operating lever 39, upper and lower toggle links 41, 43 which are pivotally connected by means of a knee pivot pin 45, a pair of tension springs 47, and an insulating handle 49. The upper toggle link 41 is pivotally connected to a movable releasable arm or trip member 51 by means of a pin 53. The releasable arm 51 is pivotally supported on the frame 37 by means of the pivot pin 55. The other end of the releasable arm 51 includes a latch surface 57 which is held in a latch position by a roller 59 which is part of a trip means generally indicated at 61, as shown more particularly in FIG. 2.

The trip means 61 (FIG. 2) comprises a frame 63, the roller 59, a latch lever 65, a linkage mechanism 67, a reset lever 69, and a magnetic trip actuator 71. The frame 63 is a U-shaped member, the lower intermediate portion of which is secured by a bolt 72 extending into the base 9.

In accordance with this invention, the latch lever 65 is pivotally mounted on a pin 73 which extends between the spaced upright portions of the frame 63, and as shown more particularly in FIG. 3, comprises spaced parallel portions 65a and 65b interconnected by intermediate portion 6'50. The portions 65a, 65b, 650, comprise an integral bifurcated member. The roller 59 is mounted on a pin-75, the ends of which are disposed in corresponding slots 77 in the lever members 650 and 65b. The axes of the slots 77 (FIG. 2) are disposed at acute angles to the point of contact 79 of the roller 59 with the latched'surface 57 and the end portions of the pin are disposed at the upper or right end of the slots 77 where the pin is biased by a pair of wire springs 81 mounted on opposite end portions of the pin 73 (FIG. 2). Thus, the roller 59 is retained in latching contact with the surface 57 of the releasable arm 51 until the lever 65 is rotated counterclockwise around the pin 73.

The left end of the lever 65 (FIG. 2) is connected to the linkage mechanism 67 which retains the lever in the latched position. The linkage mechanism 67 comprises upper and lower links 83 and 85. The pair of upper links 83 are pivotally secured to the latch lever portions 65a, 6512, by a pin 87. Two lower links 85 are part of an H-shaped member having an integral interconnecting portion 85a (FIG. 3) which serves as a reinforcing member for the spaced parallel links 85. The spaced lower links 85 are pivotally mounted on corresponding upright frame portions 63 by a pin 89. The lower ends of the upper links 83 are pivotally connected by apin,

91 to the upper portion of the lower link. In the latched position, with the roller 59 in contact with the surface 57 of the releasable arm 51, the axis of the pin 91 is slightly to the left (FIG. 2) of a line 93 passing through the axes of the pin 87, 89. Thus, upward pressure applied by the releasable arm 51 against the roller to cause the lever 65 to rotate counterclockwise and thereby release the arm, is resisted by the overcenter toggle mechanism 67, because the axis of the pin 91.

Each lower link 85 includes a projection 95, which in the latched position is in contact with the pin 87 so that downward pressure of the levers 65 on the pin 87, and ultimately upon the pin 91, is prevented from moving the pin 91 further to the left than is necessary to main tain the latched position of the releasable arm 51.

To trip the circuit breaker 7 from the closed to open condition, the pin 91 is moved to the right of the line 93 passing through the axes of the pins 87, 89. The toggle mechanism 67 then collapses to the broken line positions of the upper and lower links as shown in FIG. 2, enabling the lever. 65 to rotate counterclockwise, whereby the roller 59 rolls off of the left end of the-arm 51 to permit the arm to raise to the unlatched position, as shown by the broken line positions of parts 65, 83, 85. The force applied on the roller 59 by the arm 51 during its upward rotation causes the pin 75 to yield against the springs 81 along the slots 77 until the arm 51 is above the roller 59.

The means by which the pin 91 is moved to the right of the line 93 may include either manual or shunt trip means, such as the magnetic trip actuator 71. The manual means includes the release lever 69 and a manual or push-to-trip button 97. The release lever 69 is pivotally mounted at the upper end of a frame 99 of the mag netic trip actuator 71 where it is retained by washers 101 on frame projections 102. The lever 69 includes a down-turned portion 103 which is normally disposed adjacent to the interconnecting portion 85a of the lower link lever 85. Accordingly, when the manual button 97 is depressed against the horizontal portion of the lever 69, the downturned portion 103 thereof moves the pin 91 to the right of the line 93, thereby releasing the latched arm 51.

Another embodiment of the invention is shown in FIGS. 4 and and differs from that of FIGS. 2 and 3 in that the axis of the pin 91 is disposed slightly to the right of the axis line 93, when the lever 51 is in the latched position as shown. To prevent the trip means 61 from unlatching the lever 51 the lower links 85 include projections l05 which are restrained by the reset lever 69 from rotating clockwise to unlatch the unit. The embodiment of the lever 69 in FIG. 4 comprises an extension 107 having out-turned portions 109 (FIG. 5) which engage the projections 105 at 111. Accordingly, the trip means 61 remains in the latched position until the reset lever 69 is rotated counterclockwise, such as by the magnetic trip actuator 71 or the manual button 97. When the reset lever 69 is rotated counterclockwise, the out-turned portions 109 move out of contact with the projections 105 whereby the trip means 61 collapses to unlatch the lever 51.

Although the magnetic trip actuator 71 is described in a copending US. Pat. application Ser. No. 327,964, now US. Pat. No. 3,783.423 briefly the actuator is an electromagnetic device comprising a coil I13 and a 4 plunger 115 which when actuated by the coil moves the member a (FIG. 2) to the right thereby unlatching the arm 51. In FIG. 4, the plunger 115 moves the lever portion 103 counterclockwise to lift the out-turned portions 109 out of blocking position of the projections and to trip the releasable arm 51.

In each pole unit of the circuit breaker, a current sensing transformer 117 (FIG. 1) is disposed over the conductor 31 to sense the overload current and operate through another transformer (not shown) and a static circuit supported on a static circuit board 119, to energize the coil 113 of the magnetic trip actuator 71 to release the armature or plunger by a spring 121, and to thereby effect a tripping operation of the circuit breaker in response to overload current condition above a predetermined value. The tripping operation is more specifically described in the US. Pat. applications of Alfred E. Maier et al, Ser. No. 327,961, now US. Pat. No. 3,808,567 and Alan B. Shimp, Ser. No. 327,973 now US. Pat. No. 3,818,275.

Resetting the circuit breaker 7 and the trip means 61 is accomplished by the handle 49 (FIG. 1) which is rotated clockwise so that a flange 123 on the operating lever 39 contacts and rotates the releasable arm 51 until the latch surface 57 is again in position for contact with roller 59. Simultaneously, a portion 49a of the handle engages the lever extension 107 to return the release levers to their latched positions.

Accordingly, the device of the present invention provides means of more compact construction and provides for a force reduction through the latch structure with reduced friction.

What is claimed is:

l. A circuit breaker for controlling an electric circuit comprising relatively movable contacts, a releasable arm to effect automatic opening of the contacts, a trip device for latching the releasable arm and comprising a roller, a latch lever, and a linkage mechanism; the roller being mounted on the latch lever for retaining the releasable arm in the latched position, the latch lever being pivotally mounted for movement between latched and unlatched positions, the linkage mechanism comprising an overcenter toggle for holding the latch lever in the latched position, and release means operable to release the overcenter toggle so that the latch lever is movable to the unlatched position.

2. The circuit breaker of claim 1 in which the releasable arm is biased to the unlatched position so that release of the overcenter toggle effects release of the releasable arm.

3. The circuit breaker of claim 2 in which the roller is positioned proximate to one end of the latch lever, and the overcenter toggle being connected proximate to the other end of the latch lever.

4. The circuit breaker of claim 3 in which the latch lever is bifurcated with each leg including a slot extending in a direction substantially normal to the path of movement of the releasable arm, and the end portions of the roller being disposed in corresponding slots and biased toward said path of movement.

5. The circuit breaker of claim 3 in which the overcenter toggle comprises a pair of links having a knee pivot therebetween and the knee pivot being movable to the trip position upon operation of the release means.

6. The circuit breaker of claim 4 in which the overcenter toggle comprises spaced pairs of links, each pair of links comprising first and second links. each pair of links including a knee pivot, and one of each first and second links being pivoted to a corresponding bifurcated leg of the latch lever.

7. The circuit breaker of claim 6 in which the other of each first and second links is pivotally mounted on the side of the knee pivot opposite the latch lever, and the axis of the knee pivot being located on the side of a line passing through the axes of the link pivot mountings opposite the roller when the latch member is latched.

8. The circuit breaker of claim 6 in which the other of each first and second links is pivotally mounted on the an overload in the electric circuit. 

1. A circuit breaker for controlling an electric circuit comprising relatively movable contacts, a releasable arm to effect automatic opening of the contacts, a trip device for latching the releasable arm and comprising a roller, a latch lever, and a linkage mechanism; the roller being mounted on the latch lever for retaining the releasable arm in the latched position, the latch lever being pivotally mounted for movement between latched and unlatched positions, the linkage mechanism comprising an overcenter toggle for holding the latch lever in the latched position, and release means operable to release the overcenter toggle so that the latch lever is movable to the unlatched position.
 2. The circuit breaker of claim 1 in which the releasable arm is biased to the unlatched position so that release of the overcenter toggle effects release of the releasable arm.
 3. The circuit breaker of claim 2 in which the roller is positioned proximate to one end of the latch lever, and the overcenter toggle being connected proximate to the other end of the latch lever.
 4. The circuit breaker of claim 3 in which the latch lever is bifurcated with each leg including a slot extending in a direction substantially normal to the path of movement of the releasable arm, and the end portions of the roller being disposed in corresponding slots and biased toward said path of movement.
 5. The circuit breaker of claim 3 in which the overcenter toggle comprises a pair of links having a knee pivot therebetween and the knee pivot being movable to the trip position upon operation of the release means.
 6. The circuit breaker of claim 4 in which the overcenter toggle comprises spaced pairs of links, each pair of links comprising first and second links, each pair of links including a knee pivot, and one of each first and second links being pivoted to a corresponding bifurcated leg of the latch lever.
 7. The circuit breaker of claim 6 in which the other of each first and second links is pivotally mounted on the side of the knee pivot opposite the latch lever, and the axis of the knee pivot being located on the side of a line passing through the axes of the link pivot mountings opposite the roller when the latch member is latched.
 8. The circuit breaker of claim 6 in which the other of each first and second links is pivotally mounted on the side of the knee pivot opposite the latch lever, and the axis of the knee pivot being located on the same side of a line passing through the axes of the link pivot mountings as the roller when the latch member is latched, and the release means having strike edges for preventing unlatching of the releasable arm when the release means is inoperative.
 9. The circuit breaker of claim 1 in which the release means comprise electromagnetic means responsive to an overload in the electric circuit. 